Sanibel’s Endemic Rice Rat Remains Elusive
Sanibel Island rice rats live in an extremely limited, and unfortunately shrinking habitat on Sanibel. Historically, Sanibel was mostly an open canopy ridge and swale system with sparse trees throughout, except along the Sanibel River corridor and the mangrove forests on the bayside. This endemic rat species prefers open canopy cordgrass (Spartina bakeri) marshes that must be maintained by fire to keep them from transitioning to a closed canopy buttonwood (Conocarpus erectus) forest with interspersed shrubby vegetation, such as saltbush (Baccharis halimifolia) and wax myrtle (Myrica cerifera).
When the largest study on Sanibel Island ended in 2018, they occurred in limited numbers in an area generally bounded by Tarpon Bay Road, West Gulf Drive, and Legion Curve. The rice rat lives on lands owned by SCCF, J.N. “Ding” Darling National Wildlife Refuge, and the City of Sanibel, and our management practices in these freshwater wetlands are primarily based on the conservation of this endemic subspecies. By managing wetlands for rice rats, many native wildlife species, such as wading birds, amphibians, and macroinvertebrates benefit from these same open canopy wetlands.
Sanibel rice rats are not to be confused with the more common native rat, the hispid cotton rat (Sigmodon hispidus), which is omnivorous but primarily eats vegetation. These are the rats of dry, open grasslands. The other rat on Sanibel—the one that gives rats a bad name—is the black rat (Rattus rattus), typically referred to as a roof rat or palm rat. These non-native rats arrived in ships from Great Britain to the New World in colonial days and have been a nuisance ever since. These are the rats on the island that enter homes and businesses and cause damage. Unfortunately, hispid cotton rats and Sanibel Island rice rats get lumped into the nuisance category even though they are not the rats causing issues.
Unlike the other rat species on the island, the rice rat favors a carnivorous diet, although it also consumes Spartina bakeri and other wetland plants. Predators of the Sanibel Island rice rat are raptors such as red-shouldered hawks (Buteo lineatus) and owls, as well as bobcats (Lynx rufus).